/*
 * Copyright (c) 2014-2016, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <arch_helpers.h>
#include <assert.h>
#include <css_def.h>
#include <debug.h>
#include <platform.h>
#include <stdint.h>
#include "../drivers/scpi/css_mhu.h"
#include "../drivers/scpi/css_scpi.h"
#include "css_scp_bootloader.h"

/* ID of the MHU slot used for the BOM protocol */
#define BOM_MHU_SLOT_ID        0

/* Boot commands sent from AP -> SCP */
#define BOOT_CMD_INFO    0x00
#define BOOT_CMD_DATA    0x01

/* BOM command header */
typedef struct {
    uint32_t id : 8;
    uint32_t reserved : 24;
} bom_cmd_t;

typedef struct {
    uint32_t image_size;
    uint32_t checksum;
} cmd_info_payload_t;

/*
 * Unlike the SCPI protocol, the boot protocol uses the same memory region
 * for both AP -> SCP and SCP -> AP transfers; define the address of this...
 */
#define BOM_SHARED_MEM        PLAT_CSS_SCP_COM_SHARED_MEM_BASE
#define BOM_CMD_HEADER        ((bom_cmd_t *) BOM_SHARED_MEM)
#define BOM_CMD_PAYLOAD        ((void *) (BOM_SHARED_MEM + sizeof(bom_cmd_t)))

typedef struct {
    /* Offset from the base address of the Trusted RAM */
    uint32_t offset;
    uint32_t block_size;
} cmd_data_payload_t;

static void scp_boot_message_start(void)
{
    mhu_secure_message_start(BOM_MHU_SLOT_ID);
}

static void scp_boot_message_send(size_t payload_size)
{
    /* Ensure that any write to the BOM payload area is seen by SCP before
     * we write to the MHU register. If these 2 writes were reordered by
     * the CPU then SCP would read stale payload data */
    dmbst();

    /* Send command to SCP */
    mhu_secure_message_send(BOM_MHU_SLOT_ID);
}

static uint32_t scp_boot_message_wait(size_t size)
{
    uint32_t mhu_status;

    mhu_status = mhu_secure_message_wait();

    /* Expect an SCP Boot Protocol message, reject any other protocol */
    if (mhu_status != (1 << BOM_MHU_SLOT_ID)) {
        ERROR("MHU: Unexpected protocol (MHU status: 0x%x)\n",
            mhu_status);
        panic();
    }

    /* Ensure that any read to the BOM payload area is done after reading
     * the MHU register. If these 2 reads were reordered then the CPU would
     * read invalid payload data */
    dmbld();

    return *(uint32_t *) BOM_SHARED_MEM;
}

static void scp_boot_message_end(void)
{
    mhu_secure_message_end(BOM_MHU_SLOT_ID);
}

int scp_bootloader_transfer(void *image, unsigned int image_size)
{
    uint32_t response;
    uint32_t checksum;
    cmd_info_payload_t *cmd_info_payload;
    cmd_data_payload_t *cmd_data_payload;

    assert((uintptr_t) image == SCP_BL2_BASE);

    if ((image_size == 0) || (image_size % 4 != 0)) {
        ERROR("Invalid size for the SCP_BL2 image. Must be a multiple of "
            "4 bytes and not zero (current size = 0x%x)\n",
            image_size);
        return -1;
    }

    /* Extract the checksum from the image */
    checksum = *(uint32_t *) image;
    image = (char *) image + sizeof(checksum);
    image_size -= sizeof(checksum);

    mhu_secure_init();

    VERBOSE("Send info about the SCP_BL2 image to be transferred to SCP\n");

    /*
     * Send information about the SCP firmware image about to be transferred
     * to SCP
     */
    scp_boot_message_start();

    BOM_CMD_HEADER->id = BOOT_CMD_INFO;
    cmd_info_payload = BOM_CMD_PAYLOAD;
    cmd_info_payload->image_size = image_size;
    cmd_info_payload->checksum = checksum;

    scp_boot_message_send(sizeof(*cmd_info_payload));
#if CSS_DETECT_PRE_1_7_0_SCP
    {
        const uint32_t deprecated_scp_nack_cmd = 0x404;
        uint32_t mhu_status;

        VERBOSE("Detecting SCP version incompatibility\n");

        mhu_status = mhu_secure_message_wait();
        if (mhu_status == deprecated_scp_nack_cmd) {
            ERROR("Detected an incompatible version of the SCP firmware.\n");
            ERROR("Only versions from v1.7.0 onwards are supported.\n");
            ERROR("Please update the SCP firmware.\n");
            return -1;
        }

        VERBOSE("SCP version looks OK\n");
    }
#endif /* CSS_DETECT_PRE_1_7_0_SCP */
    response = scp_boot_message_wait(sizeof(response));
    scp_boot_message_end();

    if (response != 0) {
        ERROR("SCP BOOT_CMD_INFO returned error %u\n", response);
        return -1;
    }

    VERBOSE("Transferring SCP_BL2 image to SCP\n");

    /* Transfer SCP_BL2 image to SCP */
    scp_boot_message_start();

    BOM_CMD_HEADER->id = BOOT_CMD_DATA;
    cmd_data_payload = BOM_CMD_PAYLOAD;
    cmd_data_payload->offset = (uintptr_t) image - ARM_TRUSTED_SRAM_BASE;
    cmd_data_payload->block_size = image_size;

    scp_boot_message_send(sizeof(*cmd_data_payload));
    response = scp_boot_message_wait(sizeof(response));
    scp_boot_message_end();

    if (response != 0) {
        ERROR("SCP BOOT_CMD_DATA returned error %u\n", response);
        return -1;
    }

    VERBOSE("Waiting for SCP to signal it is ready to go on\n");

    /* Wait for SCP to signal it's ready */
    return scpi_wait_ready();
}
